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Multiple Domains emails on single Exchange 2010 server

Hello All,

I have a challenge to complete and need input from you guys:

Three domains registered as  - abc.com, def.com and ghi.com belong to the same company but the businesses of all three domains are distinct and independent, very separate from each other. The emails were hosted with hosting company so there were no issues. Now the company wants to bring emails in house on its own exchange server. The new set is as below.

Existing in house functional Active directory domain for internal user's authentication and directory services:
All the users reside in this domain and there is a domain controller for that purpose.
Microsoft Exchange 2010 is installed in this domain - abc.local
MX records are changed with the service provider hosting DNS zone file.

The part where I need help is:  how to configure other three domains users (which are just the mail boxes, no actual users).

I tried to add new domains in accepted domains list - okay.
When tried to create a mail box it asks to create user and only option for a user name is the ........@abc.local, the domain where the exchange server is installed.

Thanks in advance for your help....
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8/22/2022 - Mon

I tried to add correct zone of Microsoft Exchange Server 2010, but for some reason web site "Add Zone" was not displayed correctly and I could not select the correct zone. Please move my question to correct zone.

just create the users, and then go in via exchange management and change the email aliases associated with the account.

OWA need to be accesible for each user seperatly.

Creating email alias will bring all the mails to one single mail box, there is no seperation of mails based on business unit.

This is the best money I have ever spent. I cannot not tell you how many times these folks have saved my bacon. I learn so much from the contributors.

no..create the users, then edit or remove the aliases you dont want.
eg create moh - with one alias moh@abc.com
moh2 with moh@def.com
moh3 with moh@ghi.com
and give the main moh full access and send as rights to the three users

Thanks for the input and sorry about not understanding it completley

Below is what I am trying to do and getting struck

Creating user: I can only create mail box for the domain in which exchange server existsn(abc.local).
Active directory domain is abc.local

Exchange Management Console > Recepient Configuration > Mailbox > New mail box > Wizard Starts > Select User Mail Box > Next > Select New User > Next >Enter User Information

While providing the User details, the only option for user logon name is with @abc.local...(user have to be in abc.com domain whereas we need user names from different domain, because if they are in alias then alises will not have OWA access.

Please advise if this is correct?

Can you please provide steps to complete this configuration so that

Only one user will be in main domain (abc.local)
All other users like user@def.com, user@ghi.com have only mail boxes as user@def.com and user@ghi.com
All three users should have their own access to OWA.

Sorry for having limited experince in exchange 2010 and thanks for your detiled steps in helping me out.


Please check out this Technet document


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create user in EMC

Hello gortm001,

Thanks for the link. This describes how to create policy to be applied for the users. Next steps is where to create users as just mail boxes (no log on required) for other domains (user@def.com, user@ghi.com). See pic above, the only option is @abc.local.


create them as normal users, with a mailbox, but set the security groups appropritely (typically remove them from domain users and create a group called restricted access)
that way they wont be able to log in etc, and only have access to mail.
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Thanks for solution. It worked for send but I may be missing something as I am not receving email.

Send out email from account moh@abc.com to external addresses, all okay. When send from external addreses to moh@abc.com, did not receive in mail box, also no error or bounced back messages in the sender external emails. \
Checked MX record, correctly forwarding to Exchange server.
Is there any way I can trace the path of email to see where it get struck.

Outbox of sender external email is clear.


maybe another question.

however..are you 100% sure the mx records are pointing to the new server.
how long ago were the mx records changed?
is port 25 beeing correctly forwarded from the router to your exchange server?
from the outside world try command prompt:
telnet mail.abc.com 25
and see if you are getting a response from the ex server

correct, that is certainly another question. Thanks for all for the input.
I have get this working, the issue was "MX Records were not updated correctly" and need ISP involvement to get it correct. It was replication problem on their end.

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